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Garrett Hughes
Garrett Hughes
Python Development Techdegree Student 32,971 Points

Can't figure out OOP instances challenge

I keep getting "TypeError: sequence item 0: expected str instance, FakeFloat found". How do I get around the fakefloat?

#Assuming x will be something like: ["apple", 5.2, "dog", 8]
#defining function
def combiner(x):
    #variable for numbers
    adder = 0
    #list for the words
    news = []
    #Looping through x
    for i in x:
        #If 'i' is an int, float, or str continue, else do nothing with i.
        if isinstance(i, (int, float, str)):  
            #if 'i' is a float or int add it to adder
            if type(i) is int or type(i) is float:
                #add numbers together
                adder += i
            #else append the str to the list
    #add the number to the end of the list as a string
    #Join everything together
    joiner = "".join(news)
    #return it
    return joiner

2 Answers

Steven Parker
Steven Parker
229,732 Points

This might not be a good place to use type().

When reading the documentation for type(), I found this recommendation: "The isinstance() built-in function is recommended for testing the type of an object, because it takes subclasses into account." Combining that with the warning of the challenge itself "Be sure to use isinstance to solve this as I might try to trick you." gives me the strong impression that in the actual test data there is at least one item subclassed (apparently as a "FakeFloat") in a way that would fool type().

You're very close, and if you refactor your code to make all the type determinations using isinstance() you should have no trouble passing the challenge.

Justin Wampler
Justin Wampler
4,523 Points

For anyone wondering how to shorten the code, one can use list comprehensions. Something like this:

def combiner(list_):
    return (''.join([item for item in list_ if isinstance(item, str)]) +
            str(sum([item for item in list_ if isinstance(item, (int, float))])))